Commercially available sound attenuators are not designed for direct mounting in the exhaust port of the device whose sound is to be attenuated, and accordingly elbows, nipples, or other extenders are generally required between the attenuator and the exhaust port. In part, at least, the reason for this is the design of the attenuator does not lend itself to the confined area often surrounding the exhaust port of the pneumatic device.
One of the problems in providing an attenuator for direct mounting in the exhaust port of a pneumatic device is that if provision is made for a blowout plug, the plug must be able to blow out of the attenuator without interference from the device on which the attenuator is mounted, such as an adjacent wall or other surface. In existing attenuators, the blowout plug has been mounted in the end wall which lies adjacent the pneumatic device on which the attenuator is mounted, and thus extenders or the like are required in order to mount the attenuator spaced from the pneumatic device sufficiently so that the fail safe plug could below out without interference. In addition, locating the fail safe plug in the end of the attenuator adjacent the exhaust port, necessitated the attenuator having a sufficiently large diameter to accommodate the plug, and this often interfered with adjacent wall portions or surfaces of the pneumatic device, thereby requiring extenders or the like to space the attenuator from the pneumatic device so that it could be mounted thereon.